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Title: Experimental and theoretical investigation of a radiative flat heat pipe based heat exchanger for waste heat recovery in the steel industry
Author: Almahmoud, Sulaiman
ISNI:       0000 0004 9353 7463
Awarding Body: Brunel University London
Current Institution: Brunel University
Date of Award: 2019
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Waste heat recovery in an energy-intensive industry such as steel industry contributes in enhancing energy efficiency, saving fuel bills, and reducing carbon dioxide emissions. Waste Heat recovery by radiation from hot sources is one of the most challenging applications for the state-of-the-art waste heat recovery technologies. The main objective of this study is to examine and characterise a radiative heat pipe as a viable solution for waste heat recovery in the steel industry. The research consisted of examining experimentally and theoretically two heat pipe heat exchanger systems. The first heat pipe was a lab-scale single radiative heat pipe made of stainless steel of 1 m long. The heat pipe was cooled by a water flow through a double pipe heat exchanger at the condenser section. The thermal performance of the radiative single heat pipe was investigated by testing it in a laboratory scale kiln. The kiln consisted of ceramic heaters installed at the bottom and insulted walls. The single heat pipe was studied at different heater temperatures and inclination angles. The effect of the emissivity of the heat pipe on heat recovery and thermal performance was also investigated. The influence of each factor was analysed separately showing a significant impact on the heat recovery. The other system was a flat heat pipe heat exchanger (FHP). The FHP consisted of parallel stainless-steel tubes connected by a bottom collector and a shell and tube top header. The structure of the heat pipe heat exchanger was attached to a flat stainless-steel sheet at the back forming a flat-shape heat pipe heat exchanger. The FHP was cooled by a water flow through the condenser. The FHP was mounted on a special designed stand to facilitate its testing at different heights and inclination angles. The FHP was tested in laboratory conditions to recover the heat from electrical heaters simulating hot steel to assess its heat recovery potential. In addition, the FHP was tested at a steel factory in real conditions at different steel temperatures between 450 °C and 600 °C. A theoretical modelling tool was built to predict the thermal performance of the single heat pipe and the FHP, each. The theoretical modelling was based on electrical analogy approach, and by applying the most appropriate correlations of two-phase heat transfer based on experimental evaluation. The theoretical heat recovery results were compared with the experimental results, and showed a good agreement within an error of less than 10% for the single heat pipe and 30% for the FHP The research outcomes demonstrated that the FHP is a novel technology to enhance the energy efficiency in the steel industry by reducing the energy consumption used to power cooling fans and energy used for heating purposes. The validated theoretical modelling tool can be used to predict the performance of the FHP for waste heat recovery by radiation in other industries.
Supervisor: Jouhara, H. ; Tassou, S. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Radiant heat recovery ; Heat pipe modelling ; Two-phase heat transfer ; Geyser boiling in heat pipes ; Thermal radiation